Thread feeding device for circular knitting machines



Aug. 11, 1970 c. HATAY 3,523,433

THREAD FEEDING DEVICE FOR CIRCULAR KNITTING MACHINES Filed March 22, 1967 5 Sheets-Sheet 1 Inventon C bar/es HA TAY Aug. 11, 1970 c, HATAY 3,523,433

THREAD FEEDING DEVICE FOR CIRCULAR KNITTING MACHINES Filed March 22, 1967 5 Sheets-Sheet 2 Aug. 11, 1970 c. HATAY 3,523,433

THREAD FEEDING DEVICE FOR CIRCULAR KNITTING MACHINES Filed March 22, 1967 5 Sheets-Sheet 5 C. HATAY Aug. 11 1970 THREAD FEEDING DEVICE FOR CIRCULAR KNITTING MACHINES Filed March 22. 1967 5 Sheets-Sheet 4 Aug.11, 1970 C.HATAY THREAD FEEDING DEVICE FOR CIRCULAR KNITTING MACHINES Filed March 22, 1967 5 Sheets-Sheet 5 L5 la la hb 40a 52 V #1 l United States Patent 3,523,433 THREAD FEEDING DEVICE FOR CIRCULAR KNITTING MACHINES Charles Hatay, Schaifhausen, Switzerland, assignor to Fouquet-Werk Franz & Planck, Rottenburg, Neckar, Germany, a corporation of Germany Filed Mar. 22, 1967, Ser. No. 625,110 Claims priority, applicatio: germauy, Mar. 25, 1966,

Int. Cl. Dtl4b 15/48 US. Cl. 66-132 '8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a thread feeding device for circular knitting machines having one or more thread feeding sections each provided with a feeding drum controlled in relation to its circumferential speed, the outer surface of which feeds the thread resting thereon by essentially slipless frictional drive. The drum is driven through an electro-magnetic coupling by a source of energy rotating at a constant speed corresponding to the highest requirement of the thread. The pull-off of the thread by the drum controlled, automatically in dependence on the tension of the thread, for example by a thread feeler, to

furnish an equal supply of thread to the individual working positions in circular knitting machines, and particularly to machines having more than one feeding station.

Apart from thread feeding devices comprising two meshing cogwheels, which have the disadvantage that the thread is crinkled several times and that in order to alter the feeding speed relatively large masses have to be accelerated or delayed by the cogwheels, two basically different types of thread feeding devices are used, both provided with smooth surfaced feeding drums. In one, the thread resting on the surface is fed without slip while in the other type the rate of feed is controlled by changing the slip of the thread on the outer surface of the feeding drum which rotates at a constant speed. The present invention relates to the first type.

It is the object of the invention to provide a thread feeding device which permits the control of the feeding speed in dependence on the tension of the thread in a simple manner, and which makes it possible to synchronize the feeding elements of the individual stations of a circular knitting machine with each other. Such a device may be preceded by an apparatus which controls the rate of the field, i.e. more exactly of the induction, is

The thread feeding device for circular knitting machines having one or more stations comprises a feeding drum controlled in relation to its circumferential speed, the drum surface of which feeds the thread resting thereon without slip, and which is driven through an electromagnetic slip coupling by a source of energy rotating at a constant speed corresponding to the highest requirement of thread. In accordance with the invention, the pulling effect of the slip coupling is electrically controlled automatically in dependence on the tension of the thread. In one embodiment the feeding drum is provided in a known manner with a metallic, drum-like outer surface which forms together with a magnetic system, arranged coaxially inside the drum and producing a rotating magnetic field, an adjustable eddy current coupling, the slip of which is step-wise or continuously controllable by altering the magnitude of the exciter current by the thread tension feeler.

The control of the pulling effect of the coupling may be achieved, for example, in such a manner that the thread tension feelers are oscillating due to the variations in the tension of the thread and actuate associated electrical contacts which emit electrical pulses to the exciter winding, or that a tension feeler causes a potentiometer to indicate when the position of said feeler is altered due to variations in the tension of the thread.

The magnetic system driven by a source of energy rotates with a constant speed and the intensity of the produced field is adjustable. The variation in the intensity of the field, i.e. more exactly of the induction, is achieved, in general, by changing the magnitude of the exciter current.

The construction of the present device is simple and safe in operation, so that it can be easily fitted to existing machines. Moreover, the device makes it possible to maintain the best possible stability in the tension of the thread, while during the feeding the tension of the thread can be kept constant, if required. The electrical drive of feeding drums in itself is known (see German patent publication 1,147,705). These known feeding drums are already so constructed that the feeding element is formed by a cylinder which is the rotor of an electro motor. This type of feeding drum rotates, however, at a constant and unchangeable speed, while the rate of feed of the arranged below the feeding drum and detect variations in the tension of the thread in the region between the thread is altered by changing the tension of the thread, so that the mirror-like surface of the feeding drum around which the thread is wound pulls the thread with more or less force.

The new device may be used for the supply of the thread to the individual knitting positions of a multi-station machine which can be adjusted to an absolutely constant and overall uniform value and can be maintained at this value.

Each knitting station is provided with a stroboscopic disc which can be illuminated by a stroboscopic lamp, which disc is driven by the thread and located between the thread bobbin and the thread feeding drum. The stroboscopic lamp is fed by an electrical pulse emitter (pulse counter) which is common to all stations. According to the indication of the stroboscopic discs at the individual stations, the rate of feed is adjusted to equal values by altering the position of the stitch knockingover parts, whereupon each thread, which is fed slipless by the electro-magnetically driven feeding drum, the circumferential speed of which is adjustable, is scanned by means of adjustable thread tension feelers which are arranged below the feeding drum and detect variations in the tension of the thread in the region between the relevant feeding drum and knitting station. The sensors control electrical pulse emitters which adjust electrically the circumferential speed of the relevant feeding drum to obtain a constant thread tension. The adjustable thread tension feelers of the individual stations may be set to the same thread tension, which would be the best in most cases.

In order to obtain an absolutely even tension of the thread, in particular, to eliminate peaks of tension which occur when the thread is drawn unevenly from the bobbin and which may have unpleasant results, a brake for the thread can be provided in a known manner between the thread bobbin and the feeding drum.

bined with electrical thread brake detector for disconnecting the device shown in FIG. 1; and

FIG. 5 is an electrical schematic diagram explaining the operation of the device shown in FIG. 1;

The thread or yarn stored on the bobbin 1 (FIG. 1), or any other thread package, is led by means of guide rollers 2, 3 to a thread brake 4. From there the thread is led over an electric-optical indicator 5, which operates according to the stroboscopic principle, to a feeding drum 6. As shown in FIG. 1, the thread is wound several times around this thread feeding drum 6 which is provided with a smooth and cylindrical outer surface, so that practically no slip occurs between the outer surface and the loops of the thread. Thereafter, the thread is led over a combined thread feeling and disconnecting aggregate 7 to the knitting position 8 at which an electrical knocking-over adjustment 9 is indicated in a simplified manner.

The feeding drum 6 which pulls the thread in the direction of the arrow (FIG. 1) from the bobbin 1 is connected by means of an adjustable slip coupling with a source of energy, which is formed, for example, by a belt 10 which is driven along the circumference of the machine, as shown schematically in FIGS. 1 and 3.

The drums may be driven also by means of other known driving agents, like a toothed belt or a friction wheel, or each element may be driven separately which may be advantageous for certain cases.

The construction of the feeding drum 6 and the slip coupling associated with same can be seen in FIG. 2.

A hollow axle 25 is attached to the support 24, shown in FIG. 2, which is mounted by means of screws 24' on the supporting rail 27 of the machine, shown in FIG. 1, in the inner bore of which said axle a shaft 11 is rotatable by means of two ball bearings 12, but axially unmovable. The shaft 11 is connected to a cylindrical outer drum 13 made of an electrically conductive material which is provided with a layer 14 forming the surface of the feeding drum. The layer 14 is made of a material which increases the friction of the thread wound around it, so that the thread cannot slip on the feeding drum. The drum surface 14 may also be highly polished, which may be advantageous in certain cases.

Inside the metallic cylinder 13 of the feeding drum 6 an exciter coil 15 is arranged coaxially and is surrounded by a sleeve 16 which is made of a magnetic material of good permeability, for example, iron, and has the shape of a moulded body, as shown in FIG. 2. The sleeve or moulded body 16 is constructed in two parts, the butt joints between the two parts 16 being seen at 18. The outer surface of the moulded body 16 which faces the cylindrical part 13 is constructed like the rotor of a salient pole, axial air gap type motor (sometimes referred to as a pancake type motor), which is achieved by arranging the butt joints 18 in an undulating or zigzag line.

Both parts of the moulded body 16 are attached to a hollow shaft 19 which rests by means of roller bearings 20 on the stationary hollow axle 25. The hollow shaft 19 is connected rigidly with a grooved wheel 21. The exciter coil 15 situated inside the moulded parts 16 is connected to two slip rings 22 which are provided with brush holders 23 supplying the current. The two slip rings 22 are insulated, or the grooved wheel 21 together with the axle 19 is made of an insulating material.

The mode of operation of the device is as follows:

The hollow shaft 19 and with that the moulded body parts 16 resting on the shaft and the exciter coil situated inside said parts are driven by engagement of the belt 10 (FIGS. 1 and 3), with wheel 21 at a constant speed which is higher than the highest speed required for the maximum thread consumption. The magnetic lines produced by the exciter coil 15 close around the metallic cylinder 13 of the feeding drum 6. Due to the relative movement between the metallic cylinder 13 and the field, eddy currents are induced in the cylinder 13 which results in a pulling effect between the rotating magnetic system 15, 16 and the cylinder 13. The degree of slip and with that the rate of feed of the thread is changed by altering the magnitude of the exciter current. The exciter current is adjusted by a tension feeler 17 (FIG. 4) which is provided in the thread feeling and disconnecting aggregate 7 which will be described in the following.

The thread feeling and disconnecting aggregate 7 (FIG. 4) is mounted on a common base 28, to the upper half ofwhich the thread feeler 17 is attached. This feeler comprises a two-armed lever turnable around its center of gravity, the turning axle 30 of which rests easily movable in a bearing of the base 28. The core of a spiral leaf spring 29 is attached firmly to the turning axle 30, while the outer end of the spring 29 is anchored to a block which is adjustably attached by means of a screw 32 to a holder 33 fixed to the base 28. The spring 29 acts as a counter-force to the thread which is guided, as shown in FIG. 4, over the rollers 34 and, in the direction of the arrows, to the knitting position and due to its tension exerts a diverting force on the two-armed lever. A contact finger 35 is firmly attached to turning axle 30 which can engage a resilient contact tongue 36 of an on and off switch 43 with a nonresilient counter contact 37 when the pull of the thread increases. When the thread is no longer pulled, the current supply is switched off by the switch 43.

On the lower half of the base 28 there is an electrical disconnecting device 46, the contact tongues 38 and 38a of which are short-circuited when the thread breaks.

The thread, guided by eye 39, presses the feeler roll 48 against the tension imposed by the spiral leaf spring 49,

which can be set in the same manner as the thread feeler 17.'The machine is switched off when the tension of the thread decreases or when the thread breaks, in that contact release 50 presses the lower resilient contact tongue 38 against a harder contact tongue 38a arranged above the first one.

FIG. 3 illustrates a different embodiment in which the thread feeler aggregates 17, controlling the exciter current of the coils 15, are replaced by potentiometers 26, the setting of which is controlled by levers 26a connected to rollers 26b over which the threads runs. The potentiometers 26 thus control the current through coils 15. The electrical apparatus 51, shown in FIG. 1, which is attached to the supporting rail 27 carrying the thread feeding drums, serves as a common pulse emitter for all indicating instruments 5 which operate, as mentioned above, on the stroboscopic principle. The indicating instruments are provided with perforated disc wheels which are turned by the thread. The thread is wound by almost 360 around the thread guiding groove of each of the wheels. Stroboscopic lamps are placed behind these discs driven at the rate of the thread, which lamps are supplied with electrical pulses by the central pulse emitter 51. By utilizing the known stroboscopic effect, it is possible to obtain the same rate of feed of the thread at each knitting position or station by altering the knocking-over position of the stitch. This is achieved as follows:

After the correct stitch knocking-over position has been determined at one knitting position, the pulse sequence of the apparatus 51, is adjusted to strobe the lamps so that the indicating wheel of the instrument 5 appears to be stationary. As the pulse sequence determined in this manner is fed to all indicating or stroboscopic instruments 5, ,all other knitting positions can be brought into uniformity by observing the relevant indicating instruments 5, while adjusting each stitch knocking over settingb y hand untilthe' disc wheel of each indicating instrument 5 appears to be stationary.

After the rate of feed of the thread to all knitting positions of the machine has been synchronized by the above mentioned method, any further adjustment from this basic setting adjustment) can be made automatically in dependence on the control by the thread feeler 7 or 26. This automatic adjustment is achieved as follows:

When the knitting machine is switched on, i.e. when the driving motor is switched on and the machine is ready for the knitting operation, a contactor 40 having a normally open contact 40a and a normally closed contact 41 (FIG. pulls in. The contact 40a connects the D.C. source 42, so that a voltage is developed across the terminals of the On-Otfswitch 43. This switch'43 can be actuated by the attached feeler arm 17 (FIG. 4) which is controlled by the tension of the thread. When the tension of the thread increases, the switch 43 (FIG. 5) is closed (FIG. 4), so that the exciter coil 15 of the feeding drum 6 (FIG. 2) is supplied with the current. Since the coil is rotated, the separately journalled feeding drum is pulled along by the resulting eddy current effect. Thus thread is fed to the knitting position.

A lamp 44 serves for optical indication of the eddy current coupling which, 'due to its inertia, will glow only faintly, since switch 43 is connected only for short instants.

When the tension of the thread decreases, the feeler arm 17 connected to switch 43 alters its position so that the contacts 36, 37 are opened. Consequently, the feeding drum 6 of the thread feeding device is no longer pulled along.

The continuous interaction between the on and oif connection of the switch 43 in accordance with the embodiment of FIGS. 1 and 4, results, in general, in an evenly controlled speed of the feeding drum and with that in a corresponding control of the total feed, i.e. the quantity of thread fed to the respective other knitting positions. The tension of the thread, therefore, adjusts automatically the feed of thread.

A diode 45 (FIGS. 1 and 5) connected in parallel to the exciter coil 15 (FIG. 2) cuts the voltage peaks occurring when the switch 43 (FIG. 4) opens and prevents burning of the contacts.

An electrical disconnecting device 46 (FIG. 4) comes into operation, for example, when the thread breaks, to stop the machine. Contactor 40 opens, and contact 41 will energize the contacts of relay 47. Relay 47 has its coil connected by means of conductors 52- parallel to the usual braking magnet of the machine, not shown in the drawings. The relay 47 thus supplies D.C. voltage to the exciter coils 15 independently of switch 42. As the exciter coil 15, which is driven from the machine, comes to rest when the machine is stopped, the magnetic field of the now stationary energized coil acts as a brake on the still rotating feeding drum 6, so that the feeding of the thread is quickly stopped.

The knocking-over position can be adjusted, starting from the 0 adjustment, in the plus and minus direction. Adjustment is also possible from pulse apparatus 51, simultaneously and synchronously aifecting all knitting positions. For this purpose, small adjusting motors 9 (FIG. 1) are provided at each knitting position connected to apparatus 51 which adjust the knocking-over device in accordance with the pulse sequence set as above described. The control system also may be so constructed, that the adjusting motors 9 are included in the control circuit of the feeding drum 6, in order to maintain the rate of feed of the thread constant.

Although the synchronization of the feed of the thread to the individual knitting positions of a multi-system machine is described in the foregoing, it is, of course,

also possible to synchronize a number of separate machines having one system each. When the same types of yarn are used for the same types of articles, all machines which are synchronized in the above manner will produce 'an unchanged quality of material over a long period.

I claim:

, 1. For combination with a circular knitting machine having a plurality of thread feeding stations to supply thread to the needles of the machine, a thread feeding arrangement for each of said stations, each of said thread feeding arrangements including:

a thread feeding drum (6) having a surface (14) adapted to have the thread looped therearound in essentially non-slipping engagement;

means (10, 21) to provide rotary energy rotating at constant speed and corresponding to the highest speed requirement of thread feed;

an electromagnetic slip coupling interconnecting said drum (6) and said drive means;

a source of electrical power;

and means sensing thread tension (7 or 26);

characterized in that said drum includes a metallic cylinder (13) and said electromagnetic slip coupling includes means (15) generating a rotating electromagnetic field located inside said cylinder and in inguctively coupled relation with said metallic cylinand means coupled to said thread tension sensing means controlling a characteristic of the current through said electromagnetic field in dependence on sensed thread tension,

whereby said coupling between the field generating means and the metallic cylinder will be eddy current generated in said drum, the tightness of coupling, and thus slip of the drum with respect to said rotating field, being determined by a characteristic of the current through the electromagnetic field gencrating means and thus being controlled by thread tension and whereby the feeding of the thread by each feeding arrangement is independent of the variations of the feed in the others.

2. Thread feeding arrangement according to claim 1 wherein said thread tension sensing means includes a support (7), a tension feeler wheel (34) engaged by a thread and movably mounted on said support and changmg position in accordance with tension of the thread against said wheel;

a switch (36, 37, 43);

and means (35) sensing the position of said wheel and engaging said switch to open and close said switch in accordance with said tension, said switch being connected to control electrical current through said electromagnetic field generating means.

3. Thread feeding arrangement according to claim 2, including an adjustable spring connected to said feeler wheel and adjustably biasing said wheel against said thread.

4. Thread feeding arrangement according to claim 1 wherein said means providing rotary energy includes a mechanical drive means driven from the circular knitting machine, and said electromagnetic field generating means comprises a coil driven by said drive means, said source of electrical power including means applying direct current to said coil; and said thread tension means includes means controlling application of electrical energy to said coil to vary the field strength of said electromagnetic field.

5. Thread feeding arrangement according to claim 1 wherein said means providing rotary energy includes a drive means, and said electromagnetic field generating means comprises an exciter coil arranged coaxial to said drum (6), a sleeve-like moulded body made of magnetic material of good permeability surrounding said coil, the outer surface of said body facing the metallic surface of said feeding drum being formed in interdigited sections;

and said coil being connected to and driven by said drive means. 6. Thread feeding arrangement according to claim 1 wherein said means providing rotary energy includesa drive means driven by the circular knitting machine, said machine further including a plurality of hollow bearing stubs, one each associated with a feeding station; and said electromagnetic field generating means include rotating exciter coils mechanically connected to said drive means and journalled on said stubs, said drums being mounted on bearings supported inside said stubs. 7. Thread feeding arrangement according to claim 1 further including means driven by the thread delivered to each said station (5) indicating the rate of feed of the thread;

means (51) generating a pulse sequence proportional to said rate of feed of one of said knitting stations;

and means connected to and applying said pulse sequence to the others of said thread feed rate indicating means, whereby departure of rate of feed of the various knitting stations with respect to each other can be observed.

8. Thread feeding arrangement according to claim 7 wherein each said thread feed indicating means includes 9 ROBERT R.

a drum havinga thread looped therearound, and. strobo 'scopic disc driven bysaid drum and illuminated by a strobe lamp;

from said initial thread feed. f

References Cited 'UNITED'STATES PATENTS? I 5/1941 vParvin'etal; a 6/1963 Schmidt' 66'132 XR FOREIGN PATENTS 1/1955 "Great-Britain; 3/1961 Great Britain. MACKEY, Primary Ekaminer US. 01. XQ RQ UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3, 523,433 Dated August 11, 1970 Inventor) Charles Hatay It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 36 after "drum" insert is line fil change to read of feed per station, for example of a-dmown type. Subject matter of the Present Invention: Column 2, cancel lines 34 and 35 Column 5 line 55, "42"1 should read 43 same line 55 "the" should read each Column 8 line 1, after "and" insert a Signed and sealed this 11th day of April 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM Po'wso (L691 uscomwoc 60376 P69 U.S, GOVERNMENT FIINIING OFFICE ll. O-lil-SS 

